Carl Westin

5-3 Ecological displays in ATC CD&R 93 go” areas on a two-dimensional geospatial (map) display (e.g., complexity maps, 230 and the PHARE Problem Solver/HIPS for conflict resolution 231 ). They have, how- ever, not been developed as part of the EID framework. A good example of a similar EID derived application, originally developed as a tactical obstacle avoidance inter- face for pilots, is the Solution Space Diagram (SSD). 232 The SSD is described in detail in Appendix B. The ATC SSD visualizes a selected aircraft’s maneuverability constraints, based on the relative position of other aircraft. By explicitly showing the constraints af- fecting a selected aircraft’s trajectory, the SSD accomplishes the strenuous cognitive work involved in trajectory extrapolation that controllers previously have been re- quired to do. The SSD has been shown to reduce novice controllers’ workload during high traffic loads and increase separation without reducing sector through- put. 102 Experienced controllers using the SSD have been shown to implement more conservative conflict solutions that benefit overall sector robustness, albeit at the cost of efficiency measured by the additional track miles. 233 5-3-1 Understanding and using the SSD Figure 5-1 explains the basic SSD construction in relation to a conflict between two aircraft, shown in a plan view display perspective representative to that of a con- troller. Aircraft A has been selected and therefore designated the controlled aircraft. All other aircraft are considered intruders that may interfere with the controlled aircraft. The example in Figure 5-1(a) shows aircraft B as the only intruder aircraft. Figure 5-1(b) illustrates how the SSD visualization is calculated by processing velocity plane information of both aircraft ( V 1 , V 2 ) in relation to the minimum sepa- ration zone ( protected zone ) of intruder aircraft B (typically 5 nmi in en-route). The result is a triangle-shaped area formed by the relative position of the tangent lines of aircraft B’s protected zone and the position of aircraft A (Figure 5-1(b)). This area, called the conflict zone , comprises all relative velocity vectors V relative that result in a loss of separation. The SSD presentation is derived from visualizing the conflict zone within the maneuvering envelope of the controlled aircraft A . Figure 5-1(c) shows the original triangle (TRI) SSD around aircraft A , consisting of three circles. The dashed circle, intersecting with the velocity vectors, represents the aircraft’s current speed. The inner and outer circles represent the aircraft’s ma- neuvering envelope in the horizontal plane (heading and speed). The partly shown conflict zone of aircraft B , referred to as the no-go zone , is visualized within the maximum V max and minimum V min speeds of this envelope. The no-go zones pro- vide the boundaries for safe travel by capturing the meaningful relationship between aircraft. The size and position of the no-go zone reflect the relative position, veloc- ities, and proximity of aircraft B . Red (darker grey) and orange (lighter grey) areas